The best thing you can do, is register an account on our forum, and ask for help there. Make sure you provide enough details about your problem, so we can help you out more.
If you have the Xplosiv version of Zoo Tycoon: Complete Collection, you'll notice that on the back, where the requirements are, it'll say the game doesn't work with Windows Vista. Ignore this, since the game does work on Vista, but will change the theme you're currently using (which is probably what this means). See this page for more information.